Method and apparatus for deaerating liquid

Abstract

A method for deaerating liquids, especially water, where liquid is introduced into a vacuum zone containing liquid distributing means, and where said liquid after deaeration is conveyed out from said zone is improved in that said water in said vacuum zone is ejected toward at least one vertical impingement surface of a porous material, whereby foaming is counteracted, and is directed via said porous material toward an outlet from said vacuum zone. An apparatus for carrying out said method comprises a casing (1) connected with an evacuation system (16,17,18,19), means (8) for introducing a liquid, e.g. water, into said casing and an outlet (15) for discharging treated liquid, and is characterized in that at least one vertical impingement surface of a porous material (6,11) preventing foaming is provided within said casing (1) as well as means (9) being provided for applying a liquid on the porous surface (6,11).

We claim: 
     
       1. A method for deaerating liquids which comprises (a) directing at least one stream of liquid to be deaerated into a vacuum zone and against the surface of a porous material which is coated on at least one vertically-extending impingement wall, the porous material preventing the foaming of the liquid in the streams,   (b) causing the liquid absorbed in the porous material on each vertically-extending impingement wall to flow downwardly through the porous material and concurrently become deaerated,   (c) causing the deaerated liquid to pass from the bottom of the porous material coated on each vertically-extending impingement wall downwardly into a horizontally-extending porous partition, the partition acting to prevent any liquid from the streams in step (a) from passing directly therebelow,   (d) causing the deaerated liquid to pass downwardly through the horizontally-extending porous partition and flow into a bath of deaerated liquid,   (e) withdrawing deaerated liquid from the bath of deaerated liquid, and   (f) controlling the amount of liquid in the streams of step (a) such that the surface of the bath of deaerated liquid will be located in the horizontally-extending porous partition, thereby preventing the occurrence of foam on the surface of the bath.   
     
     
       2. The method as defined in claim 1 wherein each stream of liquid in step (a) is composed of water which contains dissolved air, and wherein the bath of deaerated liquid is composed of deaerated water. 
     
     
       3. The method as defined in claim 1 wherein each vertically-extending impingement wall is annular in shape, wherein the porous material coated on each impingement wall is located on the inner side thereof, and wherein multiple streams of liquid are directed radially outwardly towards different portions of the porous material coated on each impingment wall. 
     
     
       4. An apparatus for deaerating liquids which comprises a casing,   a horizontally-extending partition formed of a porous material positioned within the casing to divide it into an upper chamber and a lower chamber,   at least one vertically-extending impingement wall extending into the upper chamber from the horizontally-extending partition, each impingement wall having a coating of a porous material which extends downwardly to contact the porous material of the horizontally extending porous partition,   at least one liquid discharge means located in the upper chamber to direct a stream of liquid to be deaerated towards a coating of porous material on an impingement wall,   pump means connected to the casing to create a vacuum in the upper chamber, and   drainage means connected to the casing to remove deaerated liquid which accumulates as a bath in the lower chamber.   
     
     
       5. An apparatus as defined in claim 4 wherein each vertically-extending impingement wall is annular in shape and the porous material is coated on the inner surface of each annularly-shaped impingement wall. 
     
     
       6. An apparatus as defined in claim 4 wherein each liquid discharge means is supplied with liquid to be deaerated from a common pipe, wherein a flow control means is located in said common pipe, and wherein a float means is located in the lower chamber and is connected to said flow control means to maintain the surface of bath of deaerated liquid in the casing such that its surface is located within the horizontally-extending partition. 
     
     
       7. An apparatus as defined in claim 4 wherein the porous material on each vertically-extending impingement wall is composed of natural or artificial fibers woven as a textile. 
     
     
       8. An apparatus as defined in claim 4 wherein a perforated support sheet extends across the casing to support the horizontally-extending partition. 
     
     
       9. An apparatus as defined in claim 8 wherein each vertically-extending impingement wall is mounted on the perforated support sheet. 
     
     
       10. An apparatus as defined in claim 4 wherein the casing includes an outer shell and an inner shell and wherein means are provided to connect the space between the outer shell and the inner shell to the pump means to create a vacuum therein. 
     
     
       11. An apparatus as defined in claim 10 wherein each vertically-extending impingement wall is annular in shape and the porous material is coated on the inner surface of each annularly-shaped impingement wall, and wherein one impingement wall is positioned adjacent the inner shell of the casing.